The present invention relates, in general, to rotary clamps having linear actuators, and more particularly, to a rotary clamp having a telescopic piston rod with predetermined adjustable lengths that correspond to predetermined rotational angles of a clamp arm.
Rotary clamps are known of the type in which linear actuator reciprocating movement is adapted to be translated into rotary movement of a clamp arm. The linear actuator is typically powered by a fluid motor, and a linkage assembly is provided that converts the linear actuator movement into rotary motion of the clamp arm. The linear motion of the linear actuator is often transmitted to the linkage assembly by a piston rod. It is known to provide a threaded engagement between the end of the piston rod and the linkage assembly so that the length of the piston rod and the linkage assembly can be incrementally adjusted to a predetermined rotational angle of the clamp arm. This often requires repeated gaging and measurement of the clamp arm to ensure that the piston rod has been properly adjusted. In addition, the amount of adjustment is limited to the amount of threaded engagement available for adjustment.
To adjust the orientation of the clamp arm, previous designs have provided for angular adjustment of the clamp arm about the clamp arm""s own pivotal axis. These designs provide for the releaseable and adjustable fastening of the clamp arm to a portion of the rotary clamp. This allows the clamp arm to be positioned and adjusted relative to its pivotal axis, but it does not allow for the adjustment of the amount or size of the rotational angle. Since the rotary clamping angle of the clamp arm is a function of the length of the linear movement of the piston arm, the rotary clamping angle is not affected by the positional mounting of the clamp arm relative to its pivotal axis.
It would be desirable to provide a rotary clamp that allows for the adjustment of the size or the amount of the rotary clamping angle of the clamp arm. It would also be desirable to provide a rotary clamp that provides a range of predetermined adjustable clamping angles in which the clamp arm could be adjusted.
The present invention overcomes the above-noted shortcomings by providing a rotary clamp having a piston rod with predetermined adjustable lengths corresponding to predetermined, adjustable clamping angles of a clamp arm. The rotary clamp provides a linear actuator wherein the piston rod transmits linear motion to a linkage assembly. The linkage assembly has one end connected to the piston rod and another end connected to the clamp arm for converting linear motion of the piston rod into rotary motion of the clamp arm.
The piston rod is telescopic in that it provides an outer shaft connected to the linear actuator and an inner shaft connected to the linkage assembly. The inner shaft is and received by an elongated bore in the outer shaft. A connector releaseably connects the outer shaft to the inner shaft at predetermined adjustable lengths corresponding to predetermined rotational angles of the clamp arm. In the preferred embodiment, the connector comprises a pin removably received by one of a plurality of corresponding apertures in the outer shaft and the inner shaft of the piston rod. The inner shaft has a plurality of apertures which extend through the inner shaft substantially perpendicular to the longitudinal axis of the inner shaft. The apertures are axially spaced along the longitudinal axis of the inner shaft at predetermined distances corresponding to predetermined angles of the clamp arm.